Sulfur-containing polymers are known to be well suited for use in aerospace sealants due to their fuel resistant nature upon crosslinking. Polysulfide sealants offer high tensile strength, high tear strength, thermal resistance and resistance to high ultraviolet light. Such sealants also offer resistance to fuel and maintain their adhesion upon exposure to fuel.
Various sulfur-containing polymers, including for example thiol-terminated sulfur-containing polymers and polysulfide polymers, are used in commercially available sealant formulations. It is often desirable to use different sealant formulations in combination to achieve the desired properties contributed by each. For example, a sealant prepared from a polysulfide has good chemical resistance, whereas a sealant prepared with a polythioether has a lower Tg and a higher service temperature. Use of sealant formulations having different chemistries together, however, can often have long-term compatibility problems. The present invention addresses this issue.